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Abstract:

The present invention relates to a process for producing a continuous
flow of hydrogen by catalyzed hydrolysis of a complex hydride, which
comprises at least adding continuously and at constant rate a fuel
solution to a reactor comprising a complex hydride stabilized on a
hydroxide on a cobalt boride catalyst that is added in excess inside said
reactor. Sodium borohydride is preferably used, the hydroxide is sodium
hydroxide and the catalyst is supported on nickel foam. Parameters and
optimal conditions to achieve continuous production of hydrogen have been
determined, which is essential in the operation of fuel cells. A facility
comprising a semi continuous reactor designed to perform the above
process, which needs no refrigeration is also an object of the present
invention, as well as a washing and reactivation process of a catalyst of
the type used in the process mentioned above.

Claims:

1. Process for producing a continuous flow of hydrogen by catalyzed
hydrolysis of a complex hydride, characterized in that it comprises at
least the following step: adding at a constant rate to a semi continuous
reactor a fuel solution comprising a complex hydride stabilized on a
hydroxide, over a cobalt boride catalyst that is added in excess to said
reactor, the hydride complex being present at the fuel solution at a
concentration comprised between 7% and 21% w/w including both limits, the
addition of said fuel solution over the catalyst being carried out at a
rate comprised between 1.5 ml/min and 5 ml/min including both limits, the
excess amount of the catalyst being comprised between 408 mg and 725 mg
including both limits, and the temperature being comprised between
42.degree. C. and 65.degree. C. including both limits.

2. Process according to claim 1, characterized in that the complex
hydride is present in the fuel solution in a concentration comprised
between 9% and 19% w/w including both limits, the addition of said fuel
solution over the catalyst is carried out at a rate comprised between 2.5
ml/min and 4 ml/min including both limits, the excess amount of catalyst
is comprised between 458 and 675 mg including both limits, and the
temperature is comprised between 47.degree. C. and 60.degree. C.
including both limits.

3. Process according to claim 1, characterized in that the complex
hydride is sodium borohydride.

4. Process according to claim 1, characterized in that the solution that
acts as fuel with which the complex hydride is stabilized is sodium
hydroxide.

5. Process according to claim 4, characterized in that the solution is
sodium hydroxide 4.5% by weight of the solution.

6. Process according to claim 1, characterized in that the cobalt boride
catalyst is supported on nickel foam.

7. Process according to claim 1, characterized in that it comprises,
prior to the addition of the fuel solution over the catalyst, the step of
stabilizing the complex hydride in the fuel solution comprising the
hydroxide.

8. Process according to claim 1, characterized in that the process
comprises extracting from the semi continuous reactor the hydrogen stream
obtained by hydrolysis and directing it to the washing means.

9. Process according to claim 1, characterized in that it comprises
directing the hydrogen stream obtained by hydrolysis to a fuel cell
continuously and at constant rate.

10. Process according to claim 9, characterized in that the fuel cell is
PEM.

11. Use of the hydrogen stream obtainable according to the process
described in claim 1 for producing energy by a fuel cell.

12. Washing and reactivation process of a cobalt boride catalyst employed
in a hydrolysis reaction of complex hydrides, characterized in that it
comprises the following steps: extracting the cobalt boride catalyst
previously used in the hydrolysis and washing it at least twice with
purified water, immersing the catalyst in a solution comprising the
complex hydride used in the hydrolysis reaction, at a ratio comprised
between 8 w/w and 14 w/w for a time comprised between 5 and 10 minutes;
and washing again the catalyst in purified water at least once.

13. Washing and reactivation process of a catalyst according to claim 12,
characterized in that said cobalt boride catalyst is supported on nickel
foam, and the complex hydride is sodium borohydride.

14. Washing and reactivation process of a cobalt boride catalyst,
characterized in that the cobalt boride catalyst is used in a process of
hydrolysis of complex hydrides according to claim 1, comprising the
following steps: extracting from the semi continuous reactor the cobalt
boride catalyst used in the hydrolysis and washing it at least twice with
purified water, immersing the catalyst in a solution comprising the
complex hydride used at a ratio comprised between 8 w/w and 14 w/w for a
time comprised between 5 and 10 minutes; and washing again the catalyst
in purified water at least once.

15. Production facility of a stream of hydrogen according to the process
described in claim 1, comprising at least the following elements: a
storage tank (1) of the fuel solution comprising the complex hydride
stabilized by hydroxide; dispensing means (2) of the fuel solution at
constant flow inside the reactor; an unrefrigerated semi continuous
reactor (3); washing means (4) of the hydrogen stream; and dispensing
means (5) of the hydrogen stream to a fuel cell, said facility being
characterized in that the unrefrigerated semi continuous reactor (3)
comprises at least: a body (6); a lid (7) with opening and closing; an
inlet (8) of the fuel solution to the body (6); and an outlet (9) of the
hydrogen stream.

16. Facility according to claim 15, characterized in that the storage
tank (1) and the unrefrigerated semi continuous reactor (3) are built
with plastic materials.

17. Facility according to claim 15, characterized in that the semi
continuous reactor (3) comprises a thermocouple (10).

Description:

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention falls within the field of generation of
hydrogen-rich gas streams by hydrolysis, particularly of hydrides and
more particularly complex hydrides, that can be used in hydrogen
production plants, combustion engines and, in particular, as fuel in fuel
cells systems where optimal results are obtained, more specifically in
PEM-type fuel cells.

BACKGROUND OF THE INVENTION

[0002] The main obstacles to the use of hydrogen as an energy carrier are
the storage, transport, distribution and choosing the ideal system to
produce energy through the same. Among the possible systems for producing
energy from hydrogen there are fuel cells, such as those of a PEM-type
(proton exchange membrane) that function efficiently converting hydrogen
(properly provided) and oxygen from the air in energy and water as a
by-product, this being environmentally benign. For these reasons, the
development of systems capable of efficiently storing and transporting
hydrogen is essential in the field.

[0010] Among the hydrides capable of releasing hydrogen by a hydrolysis
reaction, sodium borohydride (BHS) has been widely studied due to its
high content of hydrogen and its great stability in basic solutions at
room temperature. Recent reviews include a wide literature on it (B. H.
Liu, Z. P. Li, J. Power Sources 187, 2009, 527-534; U. B Demirci, O.
Akdim, J. Andrieux, J. Hannauer, R. Chamoun, P. Miele, Fuel Cells 3,
2010, 335-350). It is known that hydrogen free of carbon monoxide can be
obtained by hydrolysis of alkaline solutions of BHS in the presence of
certain catalysts using the following equation:

[0012] To optimize the conditions for hydrogen production, the total
conversion of the BHS and the gravimetric storage capacity of the
fuel+catalyst system should be maximized. While the literature provides
examples where high values of hydrogen gravimetric storage capacity are
obtained (B. H. Liu, Z. P. Li, S. Suda, J. Alloys and Compd. 468, 2009,
493-493; D. Hua, Y. Hanxi, A. Xinping, C. Chuansin, Int. J. Hydrogen
Energy 28, 2003, 1095-1100; Y. Kojima, Y. Kawai, H. Nakanishi, S.
Matsumoto, J. Power Sources 135, 2004, 36-41), these systems do not
produce hydrogen at a constant rate, which is considered highly necessary
for the fuel cell.

[0013] In regard to the devices commonly used for hydrogen production,
some reviewed patent applications describe systems based on the catalyzed
hydrolysis of sodium borohydride at high pressures (Hou, X CN101397124-A;
Jorgensen SW, US 2004052723-A1; Toyota Chuo Kenkyusho KK,
JP2003004199-A), implying that the hydrogen produced must be properly
dispensed through a valve, having problems as it is dispensed due to the
pressure drop. This obviously affects the production of hydrogen at a
constant rate.

[0014] As for the catalysts used in the production of energy using
hydrogen in fuel cells, according to a 2010 review (U. B Demirci, O.
Akdim, J. Andrieux, J. Hannauer, R. Chamoun, P. Miele, Fuel Cells 3,
2010, 335-350) in recent years papers have been published that maximize
the activity of said catalysts, but there are little activity data in
experiments of long duration, or on the possibility to reuse the catalyst
several times.

[0015] To solve these problems encountered in the field, the present
invention proposes a process of continuous production of hydrogen at
constant rate and temperature, based on adding a source of hydrogen as a
complex hydride that acts as fuel, preferably sodium borohydride,
stabilized in a hydroxide solution, preferably sodium hydroxide, over a
cobalt boride (CoB) catalyst, preferably supported on nickel foam. The
control of the reaction temperature and rate in this process, which as
mentioned are critical to optimize the conditions for hydrogen production
is based on controlling the rate of addition or aggregation of the fuel
solution to the catalyst. It is also essential to consider the
concentration of the hydride in the stabilized solution used as fuel.

[0016] Based on theoretical considerations, the present invention has
optimized the production of H2 controlling both conditions,
concentration of the complex hydride in the fuel solution and the rate of
addition of the same, under conditions of excess catalyst, so that it has
managed to maximize the total conversion of the complex hydride,
especially in the case of sodium borohydride, into H2 and the
gravimetric storage capacity of the fuel+catalyst system with constant
rates of production of hydrogen, said rates being adapted to the fuel
cell, preferably of PEM-type to which hydrogen is intended.

[0017] On the other hand, the invention proposes a hydrogen production
facility comprising a device, a semi continuous reactor, very simple in
design and that can be built with lightweight materials, having portable
applications in mind. Some works previously disclosed in the field of
industrial protection (Wang Y, CN1458059-A; Jorgensen SW, US
2004052723-A1; and Braun J, WO 2009086541-A1) include additional
components in the design for temperature and agitation control, which
makes the device a more complex system. None of the known documents
proposes to maximize the conversion of the hydride or the gravimetric
storage capacity of the fuel-catalyst system simultaneously with the
production of hydrogen at a constant rate.

[0018] In addition, we propose here a novel method and not reported so far
to reactivate the CoB catalyst, preferably supported on nickel foam, for
subsequent reuse thereof several times in the process of hydrogen
production. This method is based on two fundamental steps or stages: i)
washing and ii) chemical reactivation. Other methods of reactivation
proposed in the literature include a single washing step (J. H. Kim, K.
T. Kim, Y. M Kang, H. S. Kim, M. S. Song, Y. J. Lee, P. S. Lee, J. Y.
Lee, J Alloys and Compd. 379, 2004, 222-227 and U. B. Demirci, F Garin, J
Alloys and Compd., 2208, 5, 1), but washing as the only step does not
allow recovering the catalyst activity that has long been used and stored
without further care. The step of chemical reactivation allows the reuse
of the catalyst that has already been used and left in the highly
corrosive reaction mean for several months, which is a further innovation
of the present invention.

DESCRIPTION OF THE INVENTION

General Description

[0019] The main object of the present invention consists of a process for
the controlled production of hydrogen from the catalyzed hydrolysis of a
complex hydride, preferably sodium borohydride (according to the equation
(1) set forth in the previous section), over a wide range of rates and
under optimized conditions to maximize process performance and storage
capacity by weight and controlling the flow of hydrogen production on
demand. Thus, the optimization for minimized response times is raised.

[0020] Another object of the present invention is to design a facility for
the optimized production of H2 under constant conditions of flow,
according to the aforementioned method, characterized in that it
comprises a semi continuous reactor that does not require cooling system.
The developed device is chemically stable and safe before, during and
after the operation, and as it has been said its main advantage is that
it is not temperature controlled, i.e. it does not require refrigeration.

[0021] The hydrogen obtained in this way could feed a hydrogen production
plant or a combustion engine, although the hydrogen production process of
the present invention is preferably designed to feed a fuel cell,
preferably of the PEM type, to produce electricity.

[0022] Likewise, the present invention encompasses the development of a
method of reactivation and reuse of a cobalt boride catalyst that is used
in hydrolysis processes of complex hydrides, such as it is the case of
the present invention.

DETAILED DESCRIPTION

[0023] The present invention relates to a process for producing a
continuous flow of hydrogen through catalyzed hydrolysis of a complex
hydride, comprising at least the stage of adding a fuel solution is added
to a reactor at a constant rate, said solution comprising a complex
hydride stabilized on hydroxide on a cobalt boride catalyst; said
catalyst being added in excess inside said reactor. The complex hydride
is present in the fuel solution in a concentration comprised between 7
and 21% w/w including both limits, the addition of the fuel solution over
the catalyst being carried out at a rate comprised between 1.5 ml/minute
and 5 ml/minute including both limits, the excess amount of the catalyst
being comprised between 408 mg and 725 mg including both limits, and the
temperature being comprised between 42° C. and 65° C.
including both limits. In this way the main objective of the invention is
achieved, which is to produce a continuous flow of hydrogen that serves
as a fuel source to other devices such as a combustion engine but
preferably a fuel cell, since in this case the continuous contribution of
a flow of hydrogen is essential for its operation.

[0024] Preferably, the excess amount of the catalyst between 458 and 675
mg is added, including both limits, to achieve the generation of a
continuous flow of hydrogen within the reactor. Also preferably, the
concentration of hydride in the fuel solution is comprised between 9% and
19% w/w including both limits, adding said solution over the catalyst at
a rate comprised between 2.5 and 4 ml/min, including both limits.

[0025] If the previous preferred features are integrated in a single
embodiment of the invention (i.e., if the concentration of hydride in the
fuel solution is comprised between 9% and 19% w/w including both limits;
the addition of said solution over the catalyst is carried out at a rate
comprised between 2.5 and 4 ml/min, including both limits; and the excess
amount of catalyst is comprised between 458 and 675 mg, including both
limits) and the temperature is regulated to be comprised between
47° C. and 60° C., including both limits, then producing a
continuous flow of hydrogen comprised between 0.25 and 1 liter/minute is
achieved.

[0026] Preferably, in either case or variants herein, the complex hydride
is sodium borohydride. It has been shown that the optimum values of
hydrogen production are achieved with sodium borohydride (BHS) as a
hydrogen source, following equation (1) set forth in this specification.

[0027] Also in a preferred manner, the solution that acts as fuel with
which the complex hydride is stabilized is sodium hydroxide. More
preferably, the solution is sodium hydroxide 4.5% w/w (in percent by
weight of the solution).

[0028] As for the catalyst of cobalt boride (CoB), it is preferably
supported on nickel foam.

[0029] The reactor is semi continuous.

[0030] In one of the most preferred embodiments of the invention, the
process of hydrogen production by hydrolysis comprises at least adding in
a semi continuous reactor a solution comprising sodium borohydride
stabilized in sodium hydroxide 4.5% w/w solution, over a cobalt boride
catalyst supported on nickel foam.

[0031] Of all the embodiments that comprise this invention, the most
preferred would consist of a process for producing a continuous flow of
hydrogen by catalyzed hydrolysis of a complex hydride, comprising at
least the stage of: [0032] adding continuously and at a constant rate
to a semi continuous reactor a fuel solution comprising sodium
borohydride at a concentration comprised between 9% and 19% w/w including
both limits, stabilized on sodium hydroxide at 4.5% by weight of
solution, over a boride cobalt catalyst supported on nickel foam that is
added in excess into said reactor in an amount comprised between 458 and
675 mg, including both limits; adding the fuel solution at a rate
comprised between 2.5 and 4 ml/min, including both limits, and the
temperature in the reactor being comprised between 47° C. and
60° C., including both limits.

[0033] The main advantage of the process presented here is to optimize the
conversion of the complex hydride and maximize the gravimetric storage
capacity to achieve the production of hydrogen at a constant rate and
controlled temperature by controlled addition of the stabilized solution
of the complex hydride, which is preferably BHS, according to theoretical
calculations.

[0034] Under conditions of constant temperature and constant flow of
hydrogen, optimizing both the performance and the storage capacity of
hydrogen is achieved by choosing the aggregation rate of the fuel
solution and the concentration of the complex hydride in the same in
suitable values, such as those shown for the preferred embodiments of the
examples illustrated in FIG. 4. This methodology is based on theoretical
considerations, including the boundary conditions of the reaction.

[0035] When working with solutions of complex hydride as a fuel, more
preferably when it comes to sodium borohydride, the hydrogen storage
capacity is a property of the solution, as long as a 100% conversion of
the complex hydride is reached. Under these conditions, the hydrogen
storage capacity of the system varies with the concentration of complex
hydride, as shown in FIG. 2 for sodium borohydride. The concentration of
the complex hydride in the fuel solution is limited by the solubility of
it, being in the case of sodium borohydride 35.5% w/w, and also the
hydrolysis product contains hydration water (NaBO2XH2O;
equation (1)), both effects limiting the theoretical storage capacity of
hydrogen to 7.3% w/w when the process is performed with sodium
borohydride.

[0036] The key for the total conversion of the complex hydride added to
the reactor as fuel in the hydroxide solution is the contribution to the
reactor of an amount of cobalt boride catalyst in excess. Then, the
optimization of hydrogen storage capacity is achieved, in excess of
catalyst, by adding, for each concentration of the complex hydride in the
fuel solution, the solution volume per minute as to provide the
stoichiometric amount of the complex hydride to produce a desired
hydrogen amount per minute.

[0037] There is a further limitation for the concentration of the complex
hydride in the fuel solution, determined by the solubility of the
hydrolysis product (NaBO2XH2O, equation (1) for the case of
sodium borohydride). The precipitation prevents the production of
hydrogen under the conditions required for the fuel cell, particularly on
those the PEM type. This limit is found for the 16% w/w BHS solution at
room temperature and can be extended if the reaction temperature is
higher.

[0038] These theoretical considerations give rise to the concentration
ranges of the complex hydride (preferably sodium borohydride) solution,
addition rate of the solution and amount of catalyst described above at
the beginning of the section "Detailed description".

[0039] In a particular embodiment of the invention described, that can
include any of the preferences outlined above, the process further
comprises stabilizing the complex hydride in the fuel solution comprising
the hydroxide, prior to the addition of the fuel solution over the
catalyst:

[0040] In another particular embodiment, that includes any of the above,
the process comprises: [0041] extracting from the reactor the hydrogen
stream obtained by hydrolysis and directing it to the washing means.

[0042] The hydrogen stream can be washed or not, a particular embodiment
of the process also comprises directing the flow of hydrogen continuously
and at constant rate to a fuel cell. Preferably, the fuel cell is PEM.

[0043] Another object of the present invention consists of the
reactivation and reuse of a cobalt boride catalyst that is used in the
processes of hydrolysis of complex hydrides, such as it may be the
process set forth herein, as the reaction product (for example, in the
case of borohydride, NaBO2XH2O, equation (1)) is deposited over
the cobalt boride catalyst throughout the process, and once the addition
of fuel solution to the catalyst surface ends, is hydroxylated to form
inactive Co(OH)2 (see equation (2)):

Co2B(s)+OH.sup.-(ac)+7H2O(l)→2Co(OH)2(s)+B(OH).sub-
.4-+3.5H2(g) (2)

[0044] For these reasons, a method for reactivating the catalyst for its
subsequent reuse is proposed here, based on the following equation (3):

2Co(OH)2(s)+BH4-(ac)→Co2B(s)+0.5H2(g)+OH.sup.-(ac)+3H2O(l) (3)

[0045] The method for reactivation and reuse of the catalyst is
characterized in that it comprises the following steps: [0046]
extracting the cobalt boride catalyst used in the hydrolysis reaction and
washing it at least twice with purified water, [0047] immersing the
catalyst in a solution comprising the complex hydride used in the
hydrolysis reaction, such as it may be sodium borohydride in the case of
this invention, in a ratio comprised between 8 w/w and 14 w/w for a time
comprised between 5 and 10 minutes; and [0048] washing again the catalyst
in purified water at least once.

[0049] Preferably, this process is applied at least once over the
catalyst, although it may be carried out at least 5 times over the same
catalyst without losing efficiency in the catalytic activity or the
degree of conversion of the BHS solution (see FIG. 4).

[0050] Washing the catalyst releases the surface of the same from debris
of the reaction product, such as it may be the NaBO2XH2O when
using sodium borohydride. As mentioned above, then the washed catalyst is
introduced into a solution of the complex hydride used in the hydrolysis
reaction, such as sodium borohydride in the present invention in order to
convert the surface Co(OH)2 into CoB, which is active again,
according to the equation (3).

[0051] This catalyst recovery protocol must be done prior to using the
same, considering that since the last use of the catalyst can pass up to
several months.

[0052] It is also an object of the present invention a production facility
of a hydrogen stream in accordance with the process described above, in
any of its variants. Said facility comprises at least the following
elements, which are presented graphically in FIG. 1a to better illustrate
an embodiment of the invention, without said figure limiting the same in
its most generic form: [0053] a storage tank (1) of the fuel solution
comprising the complex hydride stabilized by a hydroxide; [0054]
dispensing means (2) of the fuel solution at constant flow into the
reactor; [0055] an unrefrigerated semi continuous reactor (3); [0056]
washing means (4) of the hydrogen stream; and [0057] dispensing means (5)
of the hydrogen stream to a fuel cell.

[0058] The facility is characterized in that the unrefrigerated semi
continuous reactor (3) is comprised at least by: [0059] a body (6);
[0060] a lid (7) with opening and closing; [0061] an inlet (8) of the
fuel solution to the body (6); and [0062] an outlet (9) of the hydrogen
stream.

[0063] Both the fuel tank (1) as the semi continuous reactor (3) can be
built with plastic materials, thus minimizing the weights according to
the system operating conditions (hydrogen flow, time, concentration of
the fuel solution . . . ).

[0064] Optionally, said semi continuous reactor (3) may comprise a
thermocouple (10) for the simultaneous measurement of temperature.

[0065] The most unique feature of the semi continuous reactor described
here is that it is not refrigerated.

[0066] A scheme of a particular embodiment of the semi continuous reactor
(3) is shown in FIG. 1b, showing the simplicity of it. The reactor (3)
can directly dispense the constant flow required for a fuel cell, which
is preferably PEM type.

[0067] As mentioned, with the continuous addition of the fuel solution to
the reactor, controlling the rate and temperature of hydrogen production
is achieved, thus being able to dispense with the described installation
of additional heating and/or cooling systems of the reactor and with
agitation methods, since the latter is achieved by the own bubbles of the
hydrogen formed in the reactor. The reactor starts to release hydrogen
with the first drops of fuel solution added containing the complex
hydride, and once it enters into regime (2-5 minutes induction) it does
it in a stable and secure manner for all the time the addition of the
fuel lasts (see FIG. 3) until the addition stops or because the reactor
itself is completely filled.

DESCRIPTION OF THE FIGURES

[0068] With the object of contributing to a better understanding of the
invention, and according to a practical embodiment thereof, is attached
as an integral part of this description a series of figures where, with
an illustrative character and in no way limiting the invention, the
following has been represented:

[0069] FIG. 1a. Scheme of the hydrogen production facility using the
process described herein, comprising the following elements: [0070]
storage tank (1) of the fuel solution; [0071] dispensing means (2) of the
fuel solution within the reactor; [0072] unrefrigerated semi continuous
reactor (3); [0073] washing means (4) of the hydrogen stream; and [0074]
dispensing means (5) of the hydrogen stream to a fuel cell.

[0081] FIG. 2-. Graphic representation of the variation of the gravimetric
storage capacity of hydrogen with respect to the concentration of the
solution of complex hydride (BHS), in conditions of total conversion of
the hydride.

[0082] FIG. 3-. Graphic representation of the flow of hydrogen (solid
line) and temperature (dashed line) versus time for the production of
1.16 liters/minute of hydrogen for an hour, feeding a 60 W PEM-type fuel
cell during that time, according to one of the examples of embodiment.

[0083] FIG. 4-. Table comparing the conditions and the results of FIG. 3
with those of another preferred embodiment illustrated in the examples
that consists of producing 0.25 liters/minute and 0.6 liters/minute of
hydrogen for an hour, to feed a 15 W and 36 W PEM-type fuel cell
respectively during that time.

[0084] FIG. 5-. Graphic representation of the hydrogen flow versus time
for the washing and reactivation of the catalyst process, which
represents:

[0085] 5.a-. Reactivation exclusively by washing (dotted line) compared
with the example of production of 1.16 liters/minute of hydrogen (solid
line);

[0087] The supported CoB catalyst was prepared by reduction of
CoCl2.6H2O in aqueous medium by NaBH4 stabilized in NaOH.
The support chosen for the catalyst is nickel foam 1.6 mm thick, 95%
porosity.

[0088] All solutions were prepared using MilliQ® purified water. Prior
to synthesis, the support was cut into rectangles of 1 cm×2 cm and
weighed. Then it was sonicated (i.e. subjected to the action of
ultrasound) for 10 min in ethanol and 10 min in acetone for cleaning.
Then it was immersed into 10% HCl for 10 min and washed with MilliQ®
water. The support thus clean was immersed in a 30 wt %
CoCl2.6H2O solution for 10 seconds and then for another 10
seconds in a BHS 20% solution in 1% NaOH cooled in an ice bath. Then the
obtained product was washed several times. The cycle was repeated 12
times.

To increase the adhesion of the catalyst to the support without losing
catalytic activity it was subjected to heat treatment for 2 hours in an
He atmosphere at 573K (1 K/min).

Example 2

Process According to the Present Invention to Produce 1.16 Liters/Minute
of Hydrogen for 1 Hour, Under Conditions to Feed a 60 W PEM-Type Fuel
Cell During that Time, from the Hydrolysis of Sodium Borohydride in the
Sodium Hydroxide Solution Over a Catalyst Such as the One from the
Previous Example

[0089] To produce 1.16 liters/minute of hydrogen the BHS solution
stabilized with a concentration of 19% w/w in it was selected. Said
solution has associated a maximum gravimetric hydrogen storage capacity
of 4%. To work in conditions of total conversion of BHS, an excess of CoB
supported on nickel foam (675 mg catalyst) is added and to optimize the
storage capacity of hydrogen a fuel addition rate of 2.5 ml/minute is
selected (therefore dispensing an amount of BHS per minute such that in
conditions of total conversion it would produce 1.3 liters/minute of
hydrogen). Under these conditions a total conversion of the 90% BHS is
achieved and a gravimetric storage capacity of hydrogen of 3.5%. The
system temperature stabilizes at about 60° C. after the first 20
minutes and remains so during the addition of BHS, the hydrogen flow is
stabilized 2 minutes after the reaction has started (see FIG. 3)).

Example 3

Process According to the Present Invention to Produce 0.6 Liters/Minute
and 0.25 Liters/Minute of Hydrogen for 1 Hour, Under Conditions to Feed a
15 W and 36 W PEM-Type Fuel Cell Respectively During that Time

[0090] Experimental embodiments were also made under conditions to produce
0.6 liters/minute and 0.25 liters/minute of hydrogen for 1 hour. The
selected conditions are shown in the table included in FIG. 4 compared to
the conditions employed in Example 2. The results obtained of hydrogen
production rate with optimization of BHS conversion and gravimetric
storage capacity are also reflected in FIG. 4.

Example 4

Washing and Reactivation Process of the Catalyst of Example (1) Through
the Reactivation Protocol Proposed in the Present Invention, and its
Reuse in the Process of Example (2)

[0091] To reuse the catalyst of Example 1 and that is used in the process
of Example 2, stored for 6 months in the open air without any special
care, the reactivation protocol described below is carried out.

[0092] The catalyst is washed with MilliQ® water several times and
then is immersed in a solution of 9% w/w BHS in 4.5% w/w NaOH for 15
minutes. After that time, the catalyst is washed again several times and
is proceeded to be used again under the conditions described in the
Example 2. This method is performed up to a total of 5 times and the
results are equivalent to those obtained in the Example 2.

[0093] To demonstrate that the methods previously reported in the
literature, consisting exclusively of washing the catalyst, are not
sufficient to reactivate a catalyst under aggressive storage conditions
as those used in the experiments described here, FIG. 5 shows the results
obtained with the complete reactivation (5.b) proposed here, compared to
a reactivation exclusively by washing (5.a), each compared with the
original response of the catalyst in the process of Example 2.